Synthesis of fatty acids Flashcards
what is fatty acid synthesis not the reverse of
b oxidation
where does fatty acid synthesis occur
in the cystol of our liver cells and in lactating mammary glands
what are the reductants in fatty acid synthesis
NADPH
why does elongation occur
due to the sequential addition of two carbon units derived from the acetyl CoA
when does elongation stop
at 16 carbohydrates
where are enzymes attached
to a single poly peptide chain “fatty acid synthase”
how do we remove xs citrate from the TCA cycle
via the pyruvate malate cycle
how does the pyruvate malate cycle work
citrate is moved out of the matrix by a transport protein and then converted back into oxaloacetate and Acetyl CoA by ATP citrate lyase using ATP
why is the pyruvate malate cycle important
it is a way of getting citrate out of the cycle
and it is a source of NADPH production
what is insulin uprugulate
ATP citrate lyase
what is the RDS in forming fatty acids
malonyl CoA step
describe the formation of malonyl coA
CO2- biotin enzyme + acetyl coA —-> malonyl coA + biotin enzyme using the enzyme acetyl coA carboxylase( biotin) and citrate
how is the formation of of malonyl coA regulated
by a high AMP:ATP ratio
and by insulin
and glucagon and epinephrine( inhibit phosphatase)
how does a high AMP:ATP ratio regulate malonyl coA formation
as the enzyme kinase is used and ATP to inactivate the acetyl CoA carboxylase enzyme
how does insulin regulate malonyl coA formation
as insulin up regulates the enzyme phosphatase which converts the inactive form of acetyl coA carboxylase into the activated from
what is a derivative of pantothenic acid (vitamin B5)
4’ phosphopentetheine
what does 4’ phosphopentetheine carry units
acetyl and acyl units on the terminal thiol group during fatty acid synthesis
describe step 1
acetyl coA + ACP-SH via the enzyme Acetyl Coa ACP transacylase—> to form acetyl S ACP + coA
what is the end product of fatty acids synthesis
palmitate
describe step 2
the transfer from Acetyl S ACP+ enzyme SH—->acetyl s enzyme + ACP -SH
describe step 3
malonyl coA + ACP-SH—> Malonyl- S-ACP + CoA
via malonyl CoA-ACP transacylase
describe step 4
malonyl S ACP+ acetyl S enzyme —-> acetoacetyl S ACP and also removes one co2 MOLECULE
how many cycles of the fatty acid synthesis occurs to produce a 16 carbon chain
7
as 2 come from malonyl every time
what are the end products
7 CO2 PRODUCED
7 ATP USED
14 NADPH UTILISED
describe step 5 of fatty acid synthesis
acetoacetyl-S-ACP + NADPH +H+—-> Beta hydroxybutyryl ACP + oxidised NADP
via the b ketoaceyl ACP reductase
describe step 6
Beta hydroxybutyryl ACP is dehydrated to form crotonyl S ACP
describe step 7
crotonyl S ACP + NADPH +H+ —-> butyrylS ACP + oxidised NADP
what might palmitate lengthen to form
stearate 18C
where are the lengthening enzymes found
on the ER and in the mitochondria
which pathway do we use for the lengthening of short chain fatty acids
mitochondrial pathway
which three enzymes are found in the desaturation of fatty acids
NADH cytochrome b5 reductase
cytochrome b5
fatty acid desaturase
where do mammalian systems produce double bonds
at the 2,,5,6,9 positions
how can double bonds be in molecules
cis and trans
what can arachidonic acid be produced by
from linoleic acid through the destraturation and elengation
why is arachondonic acid important
important in biological signalling molecules that act as short range messengers
what is arachodonic acid converted into
prostaglandins forming an intermediate prostaglandin H2
what can prostaglandin H2 form
prostacyclin
other prostaglandins
thromboxane
what does prostacyclin do
inhibits platelet activation also a vasodilator
what do other prostaglandins do
inflammatory response production of pain and fever
what do thromboxane do
vascoconstrictor hypersensitive agent and facilitates platelet aggregation
which drugs inhibits the prostaglandin synthase
aspirin
what does aspirin inhibit
the cyclooxyrgenase activity of COX
what do NON STEROIDAL ANTI INFLAMMATORY DRUGS block
cox 2
what side effects occur when cox 2 is inhibited
stomach ulceration and kidney damage
what binds with adipocytes
monoacylglycerols
diacylglycerols
triacylglycerols
to form micelles
how dow e activate fatty acids to form TAG
BY fatty acid and fatty acyl coA synthetase and ATP to from fatty acyl COA
what is the initial accept of fatty acids during the synthesis of TAG
g3p
how is G3P produced
from glucose to DHAP and then g3P in glycolysis
OR
glycerol and glycerol kinase in the liver
describe TAG synthesis
G3P to PHOSPHATIDATE by acyltransferase
phosphatide to diacylglycerol by phosphatase and then diacylglycerol to TAG via acyltransferase
